Stock Compensation Plans (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
1998 Long-Term Incentive Plan [Member]
Summary of changes in options outstanding
Number of Shares outstanding, Beginning balance (in shares)	413,710	720,791	1,057,519
Weighted Average Exercise Price outstanding, Beginning balance (in dollars per share)	$ 19.88	$ 18.19	$ 15.13
Number of Shares outstanding, Granted (in shares)	0	0	0
Weighted Average Exercise Price outstanding, Granted (in dollars per share)	$ 0	$ 0	$ 0
Number of Shares outstanding, Exercised (in shares)	(243,659)	(306,548)	(329,728)
Weighted Average Exercise Price outstanding, Exercised (in dollars per share)	$ 18.54	$ 15.93	$ 8.26
Number of Shares outstanding, Forfeited (in shares)	0	0	0
Weighted Average Exercise Price outstanding, Forfeited (in dollars per share)	$ 0	$ 0	$ 0
Number of Shares outstanding, Expired (in shares)	(1,000)	(533)	(7,000)
Weighted Average Exercise Price outstanding, Expired (in dollars per share)	$ 14.79	$ 4.76	$ 24.31
Number of Shares outstanding, Ending balance (in shares)	169,051	413,710	720,791
Weighted Average Exercise Price outstanding, Ending balance (in dollars per share)	$ 21.82	$ 19.88	$ 18.19
Number of Shares Exercisable, Ending balance (in shares)	169,051	413,710	720,791
Weighted Average Exercise Price Exercisable, Ending balance (in dollars per share)	$ 21.82	$ 19.88	$ 18.19
2006 Long-Term Incentive Plan [Member]
Summary of changes in options outstanding
Number of Shares outstanding, Beginning balance (in shares)	1,389,598	1,060,057	709,258
Weighted Average Exercise Price outstanding, Beginning balance (in dollars per share)	$ 23.02	$ 22.89	$ 27.11
Number of Shares outstanding, Granted (in shares)	0	390,750	372,750
Weighted Average Exercise Price outstanding, Granted (in dollars per share)	$ 0	$ 23.24	$ 15.11
Number of Shares outstanding, Exercised (in shares)	(170,998)	(29,862)	(500)
Weighted Average Exercise Price outstanding, Exercised (in dollars per share)	$ 24.04	$ 21.62	$ 24.25
Number of Shares outstanding, Forfeited (in shares)	(20,087)	(22,722)	(7,166)
Weighted Average Exercise Price outstanding, Forfeited (in dollars per share)	$ 20.48	$ 19.92	$ 22.89
Number of Shares outstanding, Expired (in shares)	(9,501)	(8,625)	(14,285)
Weighted Average Exercise Price outstanding, Expired (in dollars per share)	$ 23.64	$ 29.62	$ 29.22
Number of Shares outstanding, Ending balance (in shares)	1,189,012	1,389,598	1,060,057
Weighted Average Exercise Price outstanding, Ending balance (in dollars per share)	$ 22.91	$ 23.02	$ 22.89
Number of Shares Exercisable, Ending balance (in shares)	885,003	754,622	339,365
Weighted Average Exercise Price Exercisable, Ending balance (in dollars per share)	$ 23.67	$ 24.86	$ 27.99
2010 Long-Term Incentive Plan [Member]
Summary of changes in options outstanding
Number of Shares outstanding, Beginning balance (in shares)	0
Weighted Average Exercise Price outstanding, Beginning balance (in dollars per share)	$ 0
Number of Shares outstanding, Granted (in shares)	379,425
Weighted Average Exercise Price outstanding, Granted (in dollars per share)	$ 30.66
Number of Shares outstanding, Exercised (in shares)	0
Weighted Average Exercise Price outstanding, Exercised (in dollars per share)	$ 0
Number of Shares outstanding, Forfeited (in shares)	(23,375)
Weighted Average Exercise Price outstanding, Forfeited (in dollars per share)	$ 30.66
Number of Shares outstanding, Expired (in shares)	0
Weighted Average Exercise Price outstanding, Expired (in dollars per share)	$ 0
Number of Shares outstanding, Ending balance (in shares)	356,050
Weighted Average Exercise Price outstanding, Ending balance (in dollars per share)	$ 30.66
Number of Shares Exercisable, Ending balance (in shares)	0
Weighted Average Exercise Price Exercisable, Ending balance (in dollars per share)	$ 0